1. Field of the Invention
The present invention relates to a scroll type compressor which is a coolant compressor used in freezers or air conditioners and is provided with a coil-like fixed scroll and an oscillating scroll that interlocks with the fixed scroll to form a scroll chamber, in which the volumetric capacity of the scroll chamber is varied with the orbiting motion of the orbiting scroll (a swinging movement with no self-rotation) to compress the coolant.
2. Description of the Related Art
A scroll type compressor of the prior art is provided with a drive shaft that is rotated by a driving means such as an electric motor, an oscillating scroll member that is mounted decentered, i.e. eccentrically on the drive shaft, and a fixed scroll member that interlocks with the oscillating scroll member to form a compression space (scroll chamber). The volumetric capacity of the scroll chamber is varied by moving the orbiting scroll member relative to the fixed scroll member to take in, compress and discharge the coolant. In this type of structure, the lubrication and sealing of the various sliding contact surfaces of the scroll type compressor are crucial factors.
Accordingly, the scroll type compressor disclosed in Japanese Patent Unexamined Publication No. H3-149391 includes a rotary displacement type oil pump so that a sufficient quantity of lubricating oil is reliably supplied to the bearings regardless of the flow rate of the lubricating oil supplied to the compression work space. With this, a large quantity of lubricating oil is assured even when high loads are applied to the sliding contact surface of the oscillating scroll member and the drive shaft, the main bearing in the area where the drive shaft slides against the block that secures the fixed scroll member, the thrust bearing provided in the area where the orbiting scroll member slides against the block, and the like.
However, with the scroll type compressor in the example quoted above, a problem arises if a material other than ferrite is used for the fixed scroll member and the orbiting scroll member. Materials such as an aluminum alloy are used in order to reduce weight and cost of the compressor. Due to the high back pressure on the orbiting scroll member, it is pressed towards the fixed scroll member, resulting in seizure in the area where the orbiting scroll member slides in contact with the fixed scroll member.